P2MR Assurance Lab and BIP 360 Conformance Kit

Independent conformance testing for BIP 360 (Pay-to-Merkle-Root), Bitcoin's proposed post-quantum output type. A from-scratch implementation cross-checked against the official reference on the official vectors and 2,000 random script trees found two real gaps in the reference, both fixed upstream in bitcoin/bips#2273 (merged). The conformance kit (231 cases: official vectors, spec boundaries, spend validation, seeded random trees) lets any P2MR library in any language run one command through a ~30-line adapter and get pass/fail per case; it already caught a 129-deep spend bug in bitcoinjs-lib's P2MR support. Also includes the first open cost model of post-quantum signatures (ML-DSA, SLH-DSA) as Bitcoin witness data. Funding pays for adapters for rust-bitcoin, btcd, BDK and bitcoinjs-lib, negative witness-level cases, and keeping the pack current as BIP 360 changes, so divergent implementations are caught before any activation.